Successive Raid Distribution for Single Disk Expansion with Efficient and Balanced Spare Capacity

2. The method of claim 1 further comprising locating the spares on only one of the submatrices.

3. The method of claim 2 further comprising locating the spares on the submatrix having the highest subdivision indices.

4. The method of claim 3 further comprising adding a new drive to the drive subset matrix and rotating protection group members onto the new drive starting with a next lowest unrotated subdivision index of each submatrix and proceeding from a lowest to highest subdivision index and lowest to highest drive index of the new drive.

5. The method of claim 4 further comprising creating new protection groups in individual subdivision indices freed by relocation of protection group members to the new drive.

6. The method of claim 5 further comprising splitting the drive subset matrix into two drive subset matrices and reorganizing at least one of the two drive subset matrices.

7. The method of claim 6 further comprising adding at least one new drive and creating new protection groups along freed diagonals.

9. The apparatus of claim 8 further comprising the at least one drive manager configured to locate the spares on only one of the submatrices.

10. The apparatus of claim 9 further comprising the at least one drive manager configured to locate the spares on the submatrix having the highest subdivision indices.

11. The apparatus of claim 10 further comprising the at least one drive manager configured to rotate protection group members onto a new drive starting with a next lowest unrotated subdivision index of each submatrix and proceeding from a lowest to highest subdivision index and lowest to highest drive index of the new drive.

12. The apparatus of claim 11 further comprising the at least one drive manager configured to create new protection groups in individual subdivision indices freed by relocation of protection group members to the new drive.

13. The apparatus of claim 12 further comprising the at least one drive manager configured to split the drive subset matrix into two drive subset matrices and reorganize at least one of the two drive subset matrices.

14. The apparatus of claim 13 further comprising the at least one drive manager configured to relocate protection group members along diagonals to a new drive and create new protection groups along freed diagonals.

16. The computer-readable storage medium of claim 15 in which the method further comprises locating the spares on only one of the submatrices.

17. The computer-readable storage medium of claim 16 in which the method further comprises locating the spares on the submatrix having the highest subdivision indices.

18. The computer-readable storage medium of claim 17 in which the method further comprises adding a new drive to the drive subset matrix and rotating protection group members onto the new drive starting with a next lowest unrotated subdivision index of each submatrix and proceeding from a lowest to highest subdivision index and lowest to highest drive index of the new drive.

19. The computer-readable storage medium of claim 18 in which the method further comprises creating new protection groups in individual subdivision indices freed by relocation of protection group members to the new drive.

20. The computer-readable storage medium of claim 19 in which the method further comprises creating new protection groups along freed diagonals.